Means for reducing interfering voltages in radio apparatus



July 9, 1929. F. M. SQUIRE MEANS FOR REDUCING INTERFERING VOLTAGES IN RADIO APPARATUS F' iled Feb. 2e,

I /NVENTO/P FRANK M. SQUIRE Patented July 9, 1929.

UNITED STATES PATENT OFFICE.

FRANK M. SQUIRE, OF HOLLIS, NEW YORK, ASSIGNOE TO DE FOREST RADIO TELE- PHONE & TELEGRAPH 00., OF JERSEY CITY, NEW JERSEY, A OOB-FORATION OF DELAWARE.

MEANS FOR REDUCING INTERFEBING VOLTAGES IN RADIO APPARATUS.

Application filed February 26, 1924. .Serial No. 695,286.

The objects" of this invention are to provide means for reducing interfering voltages in radio apparatus; to protect the instruments effected by such interfering voltages; to particularly protect the instrument in the radio circuit nearest to the antennae; to provide means for protecting the radio transformer; to mount the transformer in the protecting means; to provide a convenient mounting and positive grounding of the protecting means; to secure simplicity of construction and operation, and to obtain other advantages and results as may be brought out in the following description.

Referring to the accompanying drawing in which like numerals of reference indicate similar parts throughout the several views;

Figure 1 is a side elevation of my invention mounted as used;

Figure 2 is an elevation looking toward the left side of Figure 1; and

Figure 3 is a vertical central section of the protecting means.

In the specific embodiment of the invention illustrated in said drawing, reference numeral 1 indicates a panel or other support to be found in a radio apparatus or set. Mounted on the panel in the present showing is a condenser 2. This condenser includes a frame 3 which is grounded as indicated at 1. In the construction of condensers such as the one illustrated there are two opposite frames 3, 3, between which are mounted the fixed and movable plates 5, 6, respectively. The two frames 3, 3 are both made alike, and the one nearest to the panel is provided with apertures for receiving studs 7 by which the frame is mounted upon the panel and spaced there- 'from. There are therefore corresponding "apertures in the other plate 3, and I utilize these apertures by aifixing studs 8 therein at the outer ends of which I mount the fixed portion 9 of a shield designated generally by reference numeral 10. Said fixed member of the shield as shown in the present disclosure is preferably a shallow cylinder having an end wall and a rim. An outer member 11 is provided for forming with the said member an entirely closed receptacle. By reference to Figures 1 and 3 it will be noted that said outer member 11 is likewise of cylindrical construction and with an end wall and rim, but having a rim which is somewhat deeper than the rim of the fixed member. The parts are properly proportioned so that the rim of the outer member will telescopically fit within the rim of the inner member. After the parts are completely assembled the two rims may be soldered together if so desired in order to positively prevent separation of the two parts, or the two parts may be held together by frictional engagement if so desired.

I prefer to mount within the shield thus constructed a radio frequency transformer 12 centrally mounted with respect to the interior space of the said shield. The transformer preferably consists of a flat primary coil 13 upon opposite sides of which are properly spaced secondary coils 14, 14. I have shown the coils held apart and held in proper relation-to each other by means of a plurality of diametrical strips 15. In order to mount the coils in proper position said strips 15 preferably extend beyond the periphery of the coils and at each projecting end a bolt or screw 16 passes through the same and through the end wall of the outer shield member 11, with a suitable spacer 17 interposed between said end wall and the strips so as to centrally position the transformer between the end walls. It may be observed that the transformer is mounted upon the end wall of the outer member so that it can be properly positioned and secured before the said member is applied to the radio set. Likewise, the other member of the shield may be attached in place before the transformer is inserted or the other member applied.

For obtaining the proper electrical connections with the transformer, I provide a strip of insulatory material 18 carrying suitable terminals 19 which may be screws as shown, to which proper connections are made with the transformer diagrammatically indicated in Figure 3. Preferably the material comprising the end wall of the outer shield member is cut away, as indicated in Figure 3, behind the said strip of insulatory material so that the terminal devices will not be short circuited or grounded. Attention may be called at this point to the fact that the terminal device and the transformer are mounted upon the same section of the shield member so that the wiring may be completed independent of the rest of the radio apparatus and before the said section of the shield memher is mounted upon the fixed section thereof.

It is to be understood that in radio apparatus that interfering voltages are set up Where, for instance, magnetic lines of force out wires and particularly wires of the length and regularity of winding as exists in the transformer of the type described above. Furthermore, the lines of force operating upon an instrument which is in the part of the circuit nearest to the antennae have a bad effect on the operation of the apparatus because of the amplification which is obtained between said instrument'and the sound producing instrument, such as earphones. If the portion of the apparatus adjacent the antennae part of the circuit can be protected, the magnetic or radio waves cutting the other instruments of the apparatus will have less effect upon the proper operation of the apparatus.

Obviously detail changes and modifications may be made in the construction and use of my improved means for reducing interfering voltages with radio apparatus, and I do not wish to be understood as limiting myself to the exact structure shown except as set forth in the :t'ollowing claims when construed in the light of the prior art. I

Having thus described my invention, I claim i 1. In combination with a radio transformer, a shield comprising two parts for supporting, prelocating and protecting said transformer, a condenser, and means for mounting the shield on the condense'r.

2. In a radio apparatus unit of the type des *ribed the combination with a condenser of a transformer, and a shielding case for said transformer comprising two parts one of which is attached to said condenser and grounded thereto at the point of support, while the other separable part carries means to adjustably locate within said case the windings of said transformer before said two parts are slidably joined.

' FRANK M. SQUIRE. 

